Method for cleaning and regenerating a mold

ABSTRACT

A cleaning substrate for cleaning and regenerating a mold is disclosed. The mold is contaminated after repeatedly packaging the semiconductor device by making use of thermosetting resin. At least a protrusion of the substrate can substantially match with and be contained within the edges of the mold cavity of the mold when the cleaning substrate is placed in the mold.

FIELD OF THE INVENTION

The invention relates to a cleaning substrate for cleaning andregenerating a mold, and more particularly, to a cleaning substrate forcleaning a mold of a semiconductor package that can save the amount ofthe usage of the cleaning compound without changing the facilities ofthe original fabrication process.

BACKGROUND OF THE INVENTION

During the encapsulating process by making use of the mold for moldingthe encapsulant of thermosetting resin, the mold releasing agentcontained in the encapsulant of thermosetting resin can seep into theinner surface of the mold in order to release the mold. However, themold-releasing characteristic of the molding parts will be deterioratedand the molding parts will be damaged cosmetically resulting from thecontinuously repeating the encapsulating process. Consequently, thematerial layer is contaminated and the mold releasing agent become lesseffective.

To resolve the above-mentioned problems, cleaning work must beundertaken to remove the contaminated material layer that makes themold-releasing agent ineffective. For example, an encapsulant made ofthermosetting melamine resin is put in the mold so as to make thecontaminated material, which is positioned on the inner surface of themold, integrally form and solidify in order to be removed, thereby, theinner surface of the mold is cleaned.

FIG. 1 and FIG. 2 disclose a conventional semiconductor mold. As shownin FIG. 1 and FIG. 2, the semiconductor mold 10 has a pot 11 for storingencapsulant. The pot 11 is connected to a mold cavity 14 through arunner 12 and a gate 13 where the mold cavity 14 is employed for placingsemiconductor chip (not shown). When packaging a semiconductor chip, aplunger 15 is employed to press downward so as to compress theencapsulant that is liquidized to flow through the runner 12 and thegate 13, and then fill the mold cavity 14 so as to encapsulate thesemiconductor chip. Thereafter, the mold 10 is opened and the moldedproducts are taken out after the encapsulant material is hardened.

However, after the above-mentioned steps are continuously performed, acontaminated material layer is generated on the inner surface of themold 10. Especially, the contaminated material layer on the innersurface of the mold cavity 14 will cosmetically damage the moldedproducts. Therefore, it is necessary to clean the contaminated materiallayer of the mold 10. As shown in FIG. 2, when cleaning the mold 10, acleaning substrate 20 is put into the mold 10, and a cleaning compoundis injected into the mold cavity 14. As the cleaning compound issolidified, it will integrally form with the contaminated material layeron the inner surface of the mold cavity 14 and the cleaning substrate tobecome a plastic mold which is then taken out of the mold cavity 14. Theinner surface of the mold will be entirely cleaned after repeating theabove-mentioned action for around 10 to 15 times.

It is noted that the cleaning substrate 20 is generally designed in theshape of a plate that can not effectively reduce the volume of the moldcavity 14 such that it takes several times for mold injecting to fillthe mold cavity 14 of the mold 10. As a result, it unnecessarily wastesthe material of the cleaning compound.

In the light of the above-mentioned disadvantages, it is necessary toprovide a cleaning substrate for cleaning the mold of the semiconductorpackage that can save the amount of the usage of the cleaning compoundwithout changing the facilities of the original fabrication process.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a cleaning substratefor cleaning the mold of the semiconductor package that can save theamount of the usage of the cleaning compound.

To achieve the above object, the present invention provides a cleaningsubstrate for cleaning and regenerating a mold. A protrusion provided onthe substrate can substantially match with and be contained within theedges of a mold cavity of the mold when the cleaning substrate is placedin the mold while the mold is contaminated after repeatedly packagingthe semiconductor device.

In another aspect of the cleaning substrate according to the presentinvention, the profile of the protrusion is corresponding to the edgesof the mold cavity.

In one other aspect of the cleaning substrate according to the presentinvention, the cleaning substrate is made of paper.

In addition, a cleaning method provided by the present invention forcleaning a mold includes the following steps:

-   -   (a) providing a mold having at least a mold cavity;    -   (b) placing a cleaning substrate in the mold cavity wherein the        cleaning substrate has at least a first protrusion that can        substantially match and be contained within the edges of the        mold cavity;    -   (c) injecting a cleaning compound into the mold cavity of the        mold;    -   (d) hardening the cleaning compound such that the cleaning        compound is integrally formed with the cleaning substrate to        become a molding product; and    -   (e) taking the molding product out of the mold cavity by opening        the mold.

According to the cleaning substrate of the present invention forcleaning semiconductor package, when cleaning the mold, a cleaningsubstrate is put into the mold. The multiplicity of protrusions of thecleaning substrate can be substantially contained within the edges ofthe multiplicity of mold cavities of the mold. Then, a cleaning compoundis injected into the mold cavity. The cleaning substrate can reduce theamount of usage for mold injection since the protrusions are provided onthe cleaning substrate to reduce the volume of the cavity

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a top view of a conventional cleaning substrate for a mold.

FIG. 2 is a partial cross-sectional view of a conventional cleaningsubstrate for a mold of FIG. 1.

FIG. 3 is a top view of the cleaning substrate for a mold according tothe preferred embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a cleaning substrate for amold according to the preferred embodiment of the present invention ofFIG. 3.

FIG. 5 is a partial cross-sectional view of a cleaning substrate for amold according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Currently, manufacturers in the field of semiconductor generally makeuse of the conventional transfer molding to form an encapsulating memberfor packaging the chip and the substrate. Normally, a molding apparatusconnecting to the mold cavity through a runner and a gate includes a potfor placing the encapsulant. Besides, the molding apparatus provides aplurality of eject pins for ejecting the molding products out of themold cavity.

As for the molding process, firstly, the substrate with semiconductorchips attached thereon is placed into the molding apparatus. Then, theencapsulant is put in the pot with mold tightly clamped. Subsequently, aplunger in the pot is pushed to compress the encapsulant to flow throughthe runner and the gate so as to fill the mold cavity and encapsulatethe chips and the substrate. After the encapsulant is entirely filled upthe cavity, the plunger is kept still for a predetermined period of timetill the encapsulant become hardened. Afterwards, the plunger is pulledup, the mold is opened, a degating process is performed, and the moldingproduct is ejected by the use of the eject pin. However, aftercontinuously repeating the above-mentioned processes, a contaminatedmaterial layer is generated on the inner surface of the mold.

FIG. 3 and FIG. 4 show a cleaning substrate for a semiconductor mold 100according to the preferred embodiment of the present invention. As shownin FIG. 3, and FIG. 4, the semiconductor mold 100 is applicable formaking semiconductor devices having printed circuit board (PCB) such asball grid array (BGA). The mold 100 includes an upper mold 110 a havinga plurality of recesses 111 and a lower mold 110 b. When the upper mold110 a and the lower mold 110 b are closed, a mold cavity 120 is formedtherebetween at the recesses 111. In addition, the mold 100 has aplurality of pots 130, a plurality of runners 140, and a plurality ofgates 150 where the pots are connected to the mold cavities 120 throughthe runners 140 and gates 150.

As shown in FIG. 4, when cleaning the mold 100, the mold 100 is tightlyclamped to have the cleaning substrate 200 containing in the moldcavities 120. A plurality of first protrusions 210, preferably made ofpaper, are provided on the top surface of the cleaning substrate 200 andare integrally formed thereof. Each of the protrusions 210 is entirelycontained within the edges of the mold cavities 120 of the mold 100respectively. Moreover, the profile of each the protrusion 210 ispreferably corresponding to the edge of each recess 111 of the moldcavity 120 respectively. Then, a cleaning compound, such as athermosetting melamine resin, stored in the pots 130 and compressed by adownward pushing plunger 160 flows through the runner 140 and gate 150,fills the mold cavities, and also forms over the top surface of thecleaning substrate 200. After the cleaning compound is hardened to havethe cleaning compound, the contaminated material layer and the cleaningsubstrate 200 all integrally formed together to become a moldingproduct, the mold 100 is opened to have the molding products taken out.In this way, the contaminated material layer is removed from the innersurface of the mold cavity 120. Since the substrate 200 is provided withthe protrusion 210 that can effectively reduce the volume of the moldcavity 120, the saving of the amount of usage of cleaning compound canbe achieved.

FIG. 5 is a cleaning substrate for a mold according to anotherembodiment of the present invention. As shown in FIG. 5, thesemiconductor mold 100 is applicable for making semiconductor deviceshaving lead frame such as quad flat package (QFP), thin small outlinepackage (TSOP) etc. The mold 100 includes an upper mold 110 a having aplurality of first recesses 111 a, and a lower mold 110 b having aplurality of second recesses 111 b. The upper mold 111 a and the lowermold 110 b are tightly compressed to close each other such that thefirst recess 111 a and the second recess 111 b are combined to form amold cavity 120 a. In addition, the mold 100 has a plurality of pots130, a plurality of runners 140, and a plurality of gates 150 where eachof the pots 130 are connected to each of the mold cavities 120 througheach of the runners 140 and each of the gates 150 respectively.

As shown in FIG. 5, when cleaning the mold 100, the mold 100 is tightlyclamped to have the cleaning substrate 200 containing in the moldcavities 120 a. A plurality of first protrusions 210 a and secondprotrusion 210 b, both preferably made of paper, are provided on the topand the bottom surfaces of the cleaning substrate 200 respectively, andare integrally formed thereof respectively. Both of the protrusions 210a and 210 b are substantially matched with and contained within theedges of each of the first recesses 111 a and the second recesses 111 bof the mold cavities 120 a of the mold 100 respectively. Moreover, theprofiles of each the first protrusions 210 a and each of the secondprotrusion 210 b are preferably corresponding to the edges of each ofthe first recesses 111 a and the second recesses 111 b of the cavities120 a respectively. Next, a cleaning compound, such as a thermosettingmelamine resin, is stored in the pots 130. The cleaning compoundcompressed by a downward pushing plunger 160 flows through the runner140 and gate 150, and fills the mold cavities 120 a, and also forms overthe top surface of the cleaning substrate 200. After the cleaningcompound is hardened to have the cleaning compound, the contaminatedmaterial layer, and the cleaning substrate 200 all integrally formedtogether to become a molding product, the mold 100 is opened to have themolding products taken out. In this way, the contaminated material layeris removed from the inner surface of the mold cavity 120 a. Since thesubstrate 200 is provided with the protrusions 210 a and 210 b that caneffectively reduce the volume of the mold cavity 120 a, the saving ofthe amount of usage of cleaning compound can be achieved.

Although the present invention has been explained in relation to itspreferred embodiments, it is to be understood that many other possiblemodifications and variations can be made without departing from thespirit and scope of the invention as hereinafter claimed.

1-10. (cancelled)
 11. A method for cleaning a mold comprising: providinga semiconductor packaging mold having at least a mold cavity; placing acleaning substrate in the semiconductor packaging mold wherein thecleaning substrate has at least a first protrusion on the upper surfacethereof; closing the semiconductor packaging mold such that the firstprotrusion being completely received within the mold cavity; injecting acleaning compound into the mold cavity of the semiconductor packagingmold; hardening the cleaning compound such that the cleaning compound isintegrally formed with the cleaning substrate to become a moldingproduct; and taking the molding product out of the semiconductorpackaging mold by opening the semiconductor packaging mold.
 12. Themethod for cleaning a mold of claim 11, wherein the cleaning substrateis made of paper.
 13. The method for cleaning a mold of claim 11,wherein the first protrusion conforms in shape with the mold cavity. 14.The method for cleaning a mold of claim 11, wherein the cleaningcompound is melamine resin.
 15. The method for cleaning a mold of claim11, wherein the semiconductor packaging mold comprises at least an uppermold having at least a first recess, and a lower mold having at least asecond recess, and the first recess and the second recess define themold cavity when the semiconductor packaging mold is closed; thecleaning substrate further comprises at least a second protrusion on thelower surface of the substrate, the first protrusion is completelycontained within the first recess of the upper mold and the secondprotrusion is completely contained within the second recess of the lowermold when the cleaning substrate is placed in the semiconductorpackaging mold and the semiconductor packaging mold is closed.
 16. Themethod for cleaning a mold of claim 15, wherein the first protrusionconforms in shape with the first recess.
 17. The method for cleaning amold of claim 15, wherein the second protrusion conforms in shape withthe second recess.
 18. A method for cleaning a mold comprising:providing a semiconductor packaging mold having at least a mold cavity;placing a cleaning substrate in the semiconductor packaging mold whereinthe cleaning substrate is made of paper and has at least a firstprotrusion on the upper surface thereof; closing the semiconductorpackaging mold such that the first protrusion being completely receivedwithin the mold cavity; injecting a cleaning compound into the moldcavity of the semiconductor packaging mold; hardening the cleaningcompound such that the cleaning compound is integrally formed with thecleaning substrate to become a molding product; and taking the moldingproduct out of the semiconductor packaging mold by opening thesemiconductor packaging mold.
 19. The method for cleaning a mold ofclaim 18, wherein the first protrusion conforms in shape with the moldcavity.
 20. The method for cleaning a mold of claim 18, wherein thecleaning compound is melamine resin.
 21. The method for cleaning a moldof claim 18, wherein the semiconductor packaging mold comprises at leastan upper mold having at least a first recess, and a lower mold having atleast a second recess, and the first recess and the second recess definethe mold cavity when the semiconductor packaging mold is closed; thecleaning substrate further comprises at least a second protrusion on thelower surface of the substrate, the first protrusion is completelycontained within the first recess of the upper mold and the secondprotrusion is completely contained within the second recess of the lowermold when the cleaning substrate is placed in the semiconductorpackaging mold and the semiconductor packaging mold is closed.
 22. Themethod for cleaning a mold of claim 21, wherein the first protrusionconforms in shape with the first recess.
 23. The method for cleaning amold of claim 21, wherein the second protrusion conforms in shape withthe second recess.